JP3176504B2 - Method for producing chlorinated vinyl chloride resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chlorinated vinyl chloride resin, and more particularly to a method for producing a chlorinated vinyl chloride resin which is less colored upon heating.

[0002]

2. Description of the Related Art A chlorinated vinyl chloride resin (hereinafter, referred to as CPVC) is produced by chlorinating a vinyl chloride resin (hereinafter, referred to as PVC). CPVC is PV
This is an improvement on the properties of PVC, while retaining the properties of C. That is, CPVC is an improvement of the fatal defect of PVC, which is inferior in heat resistance, while retaining the excellent weather resistance, flame resistance, and chemical resistance of PVC. To elaborate on this improvement,
PVC has a low heat distortion temperature and softens when it reaches 60-70 ° or more, so it cannot be used to make, for example, a pipe through which hot water passes.
It has the advantage of being as high as 40 ° C. and therefore can be used to make hot water pipes. Therefore, CPVC is:
Wide applications are expected as an improvement in the heat resistance of PVC.

[0003] However, the conventional CPVC is not suitable for a new opening. because,
Applications that are to be newly opened, such as display panels and electronic component cases, hate slight coloring and require extremely high transparency. Conventional CPVC,
This is because, when heated to form a molded article, thermal decomposition already occurs in the early stage of heating, and the color is changed from yellow to brown, and a colorless and transparent molded article cannot be obtained. Therefore,
In order to open a new application, it was necessary to provide a CPVC having good heat stability, which hardly colored when heated and melted for molding, and gave a colorless and transparent molded article.

[0004] Attempts to obtain a thermally stable CPVC have already been made. Many are CP
At the end of the process for producing VC, after removing unreacted chlorine, the resulting CPVC was post-treated with a specific chemical.

[0005] For example, Japanese Patent Publication No. 45-38260 and Japanese Patent Publication No. 48-22997 disclose C having good thermal stability.
To obtain PVC, at the end of the CPVC manufacturing process, C
After stopping the supply of chlorine to the PVC suspension, unreacted chlorine contained in the CPVC suspension is heated by heating the obtained CPVC suspension or blowing an inert gas into the CPVC suspension. And then treating CPVC with a reducing agent such as hydroxylamine hydrochloride or sodium thiosulfate. Japanese Patent Publication No. 45-38261 teaches that after treating unreacted chlorine from a CPVC obtained by a chlorination reaction, the CPVC is treated with an olefinic hydrocarbon. According to this method, it is possible to obtain a CPVC having better thermal stability than before, but the obtained thermal stability is not sufficient.

Japanese Patent Application Laid-Open No. 61-255954 teaches that, unlike the above proposal, a stabilizer is added to CPVC to prevent coloring during heating. That is, CPVC
It is said that when boric acid or boric acid ester is added as a stabilizer to form a molded body by processing into a molded product, the thermal stability of CPVC is improved. However, its thermal stability was not sufficient.

Further, Japanese Patent Application Laid-Open No. 5-239119 discloses that
It teaches that, in a state where CPVC is dispersed in an aqueous medium, hydrazine is added while blowing nitrogen gas into the aqueous medium to obtain CPVC having good thermal stability. According to this method, it is possible to obtain a CPVC having better thermal stability than in the past, but the obtained thermal stability was not yet sufficient.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described situation, and has been made in view of the above-mentioned problems.
It was made to provide. That is, an object of the present invention is to improve the thermal stability of CPVC, and to provide a CPVC which, when heated for molding, has less initial coloring and can be obtained as a nearly colorless and transparent molded article. It was done as.

In general, when PVC is suspended in an aqueous medium and the PVC is chlorinated in a suspended state, it is usual to use no suspending agent. The reason for this is that when a suspending agent is used, it adheres to the surface of the CPVC and remains, deteriorating the thermal stability of the CPVC.

[0010]

SUMMARY OF THE INVENTION The present inventor has proposed a CPVC
By improving the production method of the above, an attempt was made to improve the thermal stability of CPVC. For that purpose, CPVC was produced using various compounds that had not been proposed so far, the thermal stability of the obtained CPVC was examined, and a measure for improving the thermal stability of the CPVC was sought.

[0011] In the production of CPVC, the inventor added sodium polystyrene sulfonate to a suspension of PVC as a raw material, and chlorinated the PVC by blowing chlorine into the suspension. Good CPVC
Was obtained. The present invention has been completed based on such knowledge.

According to the present invention, in a method of producing PVC by suspending PVC in an aqueous medium to form a suspension, and blowing chlorine into the suspension to chlorinate the PVC, sodium polystyrene sulfonate is added to the suspension. The present invention relates to a method for producing CPVC, characterized by being added.

In general, when chlorinating PVC to produce CPVC, PVC is suspended in an aqueous medium to form a suspension, and chlorine is blown into the suspension to chlorinate PVC. For this purpose, a glass lining tank with a stirrer is usually used as a container, and an appropriate amount of deionized water is put into the container, and then an appropriate amount of PVC powder is put into the container. Disperse in a medium to form a suspension. The container is then heated to raise the temperature of the suspension. Thereafter, nitrogen gas is blown into the container to replace the air in the container with nitrogen. Next, chlorine is blown into the container, and in some cases, the suspension is irradiated with ultraviolet rays from a mercury lamp to accelerate the chlorination reaction and continue stirring to accelerate the chlorination reaction.
VC is chlorinated to produce CPVC.

As the chlorination reaction proceeds, PVC gradually produces CPVC having a high chlorine content. For example, PV
When vinyl chloride homopolymer is used as C, P
Since VC contains 56.7% by weight of chlorine, if this is chlorinated, the CPVC has a chlorine content of 56.7%.
Produces various grades in excess of weight percent. Among them, those having a chlorine content of 60 to 70% by weight are preferred. The degree of progress of the chlorination reaction can be determined by measuring the concentration of hydrogen chloride produced as a by-product in the vessel. Therefore, the concentration of hydrogen chloride by-produced in the container is measured, and it is confirmed that chlorination has progressed to a desired degree, and the chlorination reaction is stopped.

According to the present invention, sodium polystyrene sulfonate (hereinafter referred to as "polyvinyl sulfonate")
The main feature of this is that PSS is added to the suspension. There is no particular limitation on the timing of the addition, and it may be at any time before the removal of unreacted chlorine from the suspension. That is, the addition may be performed before, during, or after blowing chlorine into the suspension. However, it is preferable to add it before blowing chlorine. Thus, the present invention provides that the PSS is added prior to the recovery of unreacted chlorine and thus the PSS is added to the CPVC
It differs from the prior art in that it is not used as a post-treatment agent.

PSS is a general formula

[0017]

Embedded image It is a high molecular compound represented by these. Here, Y is mostly Na, but one part is H. It is water-soluble, exhibits surface activity and antistatic properties, and can be used as a dispersant. This compound is commercially available, for example, sold by Tokuyama Soda under the trade name Chemistad SA-9.

In the present invention, it is difficult to set a clear limit on the amount of PSS used, but the preferred range is 1 to CPVC.
It is in the range of 0 to 1000 ppm. The reason is that if the amount used is less than 10 ppm, the obtained CPVC will not show a remarkable improvement in thermal stability, and if the amount used exceeds 1000 ppm, the obtained CPVC will This is because not only does it not show a sufficient improvement in thermal stability, but rather it tends to reduce thermal stability.

In the present invention, the role played by the PSS is not well understood. However, by adding PSS,
It is certain that the obtained CPVC is hardly colored during heating and melting. If you infer the reason, PSS
Is to keep the raw material PVC and the resulting particles of CPVC uniformly dispersed in the aqueous medium, and to help the chlorine to be quickly absorbed into these particles, which leads to non-uniform particles. It is believed that it will prevent chlorination.

The present invention is carried out in exactly the same manner as conventional PVC chlorination, except that PSS is added to the suspension. That is, the preparation of the suspension, the blowing of chlorine, the process of the chlorination reaction, and the post-treatment of the chlorination can be carried out in exactly the same manner as the conventional method.
For example, the chlorination reaction can be promoted by heating the suspension or irradiating the suspension with light such as ultraviolet rays while the chlorination reaction is in progress.

The PVC used as a raw material in the present invention is not limited to a homopolymer of vinyl chloride, but may be a copolymer of vinyl chloride and another monomer. As other monomers,
Vinylidene chloride, ethylene, propylene, acrylonitrile, vinyl acetate, acrylate, methacrylate, alkyl vinyl ether and the like are used.
Also, PVC may be made by any polymerization method. For example, PVC produced by a suspension polymerization method,
Both C and PVC produced by the bulk polymerization method can be used. The degree of polymerization of PVC is not a particular problem, but the average degree of polymerization by the viscosity method is 300 to 3000.
It is preferable to use those within the range of
Those having 0 to 1500 are preferred.

The aqueous medium used in the present invention may be one obtained by adding a small amount of ketones such as acetone and methyl ethyl ketone to water in addition to pure water. If necessary, a small amount of hydrochloric acid may be added from the beginning. In addition, the aqueous medium may contain a chlorinated solvent such as trichlorethylene and carbon tetrachloride.

The method of the present invention, after implementing this,
Various methods which have been used as a method for preventing coloring of CPVC can also be implemented together. For example, after carrying out the method of the present invention, hydrazine is added while blowing nitrogen gas into the suspension as taught in JP-A-5-239119, or as taught in JP-A-64-6002. The suspension can be treated by adding nitrilotriacetic acid, or, as taught by JP-A-1-131212, the suspension can be treated by adding diethylenetriaminepentaacetic acid.

[0024]

According to the method of the present invention, PVC is suspended in an aqueous medium to form a suspension.
In the method for producing CPVC by chlorinating C, the only difference from the conventional method is that PSS is added to the suspension. Can be manufactured. Moreover, in the present invention, despite the addition of PSS to the suspension, the thus obtained CPVC is less colored during heating and becomes easier to mold. Therefore, when the obtained CPVC is heated and molded, a colorless and transparent molded body can be easily obtained. As described above, the present invention provides a great advantage in that a high-quality CPVC having good heat stability can be easily obtained.

[0025]

The following describes the advantages of the method of the present invention with reference to examples and comparative examples. Hereinafter, the term “parts” means parts by weight. Whether or not the obtained CPVC has excellent thermal stability is determined by the CPV.
When C is melted by heating, it can be easily known by measuring the length of time until the CPVC is blackened and the degree of coloring and transparency of a plate having a certain thickness obtained by heating and melting. That is, it can be said that the longer the time until blackening, the lower the degree of coloring of the sheet, and the higher the transparency, the more the colorless and transparent molded article is provided. At that time, CP
The degree of coloring, transparency and blackening time of VC were measured as described below.

[0026]

[Measurement method of coloring degree] CPVC was blended at the following ratio to prepare a mixture, which was roll-kneaded at 200 ° C to form a sheet. Several sheets were stacked and pressed at 190 ° C. for 7 minutes to obtain a plate having a constant thickness. With respect to this plate, the difference in yellowness ΔYI from the standard white plate was measured with a color difference meter manufactured by Nippon Denshoku Industries Co., Ltd., and this was defined as the degree of coloring. Formulation of CPVC CPVC 100 parts Dioctyltin mercaptide (manufactured by Nitto Kasei) 3 parts Epoxidized soybean oil (manufactured by Asahi Denka) 2 parts Montanic acid partially saponified wax (manufactured by Hoechst) 0.5 part Stearyl alcohol (manufactured by Kao Corporation) 1) MBS resin (Mitsubishi Rayon Co., Ltd.) 5 parts

[0027]

[Method of Measuring Transparency] The haze of the plate obtained by the above-described method of measuring the degree of coloring was determined using a direct-reading haze computer manufactured by Suga Test Machine Co., Ltd., and this was defined as transparency.

[0028]

[Measurement method of blackening time] Using a gear oven manufactured by Toyo Seiki Co., put the sheet obtained by the above method of measuring the degree of coloring into this oven and heat it. Time.

[0029]

Example 1 (Production of CPVC) In a 300 liter glass-lined reaction tank, about 150 kg of deionized water, about 30 kg of powdered polyvinyl chloride (viscosity average degree of polymerization 700) as PVC, and 10% of PSS An aqueous solution (150 g) was charged, and the mixture was stirred to disperse PVC in water to form a suspension.
Next, the tank was heated to raise the temperature in the tank to about 70 ° C. Thereafter, nitrogen gas was blown into the tank, and the inside of the tank was replaced with nitrogen gas. Then, chlorine gas was blown into the tank, and PVC was chlorinated while irradiating the inside of the tank with ultraviolet rays from a mercury lamp. The progress of the chlorination reaction is examined by measuring the concentration of hydrochloric acid in the tank. When the chlorine content of the generated CPVC reaches about 65% by weight, the supply of chlorine gas is stopped to stop the chlorination reaction. I let it.

Thereafter, as a post-treatment step, nitrogen gas was blown into the tank to completely remove chlorine remaining in the tank.
The obtained suspension was neutralized with caustic soda, washed with water, dehydrated, and dried until the volatile matter became 0.1% by weight or less to obtain a powdery CPVC.

When this CPVC was tested by the test method described above, it was found that the degree of coloration ΔYI was 27, the transparency was 7 haze, the blackening time was 120 minutes, and the thermal stability was good.

[0032]

EXAMPLE 2 This example was carried out in substantially the same manner as in Example 1, except that the time of addition of PSS was changed one hour after the start of chlorine blowing.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 28 and the transparency was 8
The haze and blackening time were 120 minutes, and the thermal stability was confirmed to be good.

[0034]

Embodiment 3 This embodiment was carried out almost in the same manner as in Embodiment 1, except that the timing of adding PSS was immediately after the supply of chlorine was stopped. After the addition of the PSS, the mixture was stirred for only 5 minutes. Thereafter, as in the case of Example 1, nitrogen gas was blown to remove chlorine, and post-treatment was performed.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 28 and the transparency was 9
The haze and blackening time were 120 minutes, and the thermal stability was confirmed to be good.

[0036]

Example 4 This example was carried out in the same manner as in Example 1, except that a PVC having a viscosity average degree of polymerization of 900 was used as the PVC.
The only difference was that the supply of chlorine was stopped when the chlorine content of the CPVC reached about 67% by weight.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 30 and the transparency was 9
The haze and the blackening time were 130 minutes, and the thermal stability was recognized as good.

[0038]

Example 5 This example was carried out in the same manner as in Example 1, except that the suspension was maintained at 120 ° C. and the chlorination reaction was carried out without irradiation with ultraviolet light.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 26 and the transparency was 7
Since the haze and the blackening time were 120 minutes, it was recognized that the thermal stability was good.

[0040]

Comparative Example 1 This comparative example was carried out in exactly the same manner as in Example 1 except that PSS was not used.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the degree of coloring ΔYI was 45 and the degree of transparency was 1
Since 2 haze and blackening time were 100 minutes, it was recognized that thermal stability was poor.

[0042]

Comparative Example 2 This comparative example was carried out in accordance with the teaching of Japanese Patent Application Laid-Open No. 1-113112.

More specifically, in Example 1, PSS was not used. Instead, after neutralization with caustic soda in a post-treatment step, 0.3 g of diethylenetriaminepentaacetic acid was added to the suspension, and the suspension was treated at about 50 ° C. The procedure was performed differently in that the stirring treatment was performed for 3 hours.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 40 and the transparency was 1
Since 0 haze and blackening time were 100 minutes, it was recognized that thermal stability was poor.

[0045]

Comparative Example 3 This comparative example was carried out in accordance with the teaching of Japanese Patent Application Laid-Open No. 5-239119.

More specifically, in Example 1, no PSS was used, and 100% nitrogen gas was used in the post-treatment step.
While blowing at a rate of 1 liter / min, 2000 cc of a 10% by weight aqueous hydrazine solution was added to the suspension at a rate of 500 cc / min. Then, after stirring was continued for 15 minutes, the obtained suspension was neutralized with caustic soda, and thereafter CPVC was obtained in exactly the same manner as in Example 1.

When the obtained CPVC was tested in exactly the same manner as in Example 1, the coloring degree ΔYI was 32 and the transparency was 7
The haze and blackening time were 120 minutes, and the thermal stability was relatively good, but still insufficient.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-124096 (JP, A) JP-A-5-271329 (JP, A) JP-A-5-39316 (JP, A) 1613 (JP, B1) JP 5-186520 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 8/18-8/22

Claims (1)

(57) [Claims] 1. A method for producing a chlorinated vinyl chloride resin, comprising suspending a vinyl chloride resin in an aqueous medium to form a suspension, and blowing chlorine into the suspension to chlorinate the vinyl chloride resin. A method for producing a chlorinated vinyl chloride resin, comprising adding sodium polystyrene sulfonate to a suspension.